Hydraulic valve device

ABSTRACT

The invention relates to a hydraulic valve device having a valve housing ( 10 ) in which an activating piston ( 16 ) is guided in a movable manner, which activating piston ( 16 ), being actuable by an actuating device ( 18 ), activates a pilot valve ( 20 ) by means of which a fluid port (T) in the valve housing ( 10 ) can be connected to a fluid chamber ( 22 ) of a shut-off piston ( 24 ), which shut-off piston ( 24 ) activates at least one fluid-conducting connecting line ( 1, 2 ) of the valve device and has a fluid-conducting control line ( 26 ) which opens out from the connecting line ( 1, 2 ) into the fluid chamber ( 22 ) of the shut-off piston ( 24 ).

The invention relates to a hydraulic valve device having a valve housing, with a pilot piston of a pilot valve, which piston can be actuated by an actuating device, and which piston can be moved in the direction of the valve seat of the valve housing by means of a first energy storage device, by means of the pilot piston a fluid port in the valve housing being connectable to a fluid chamber of a shut-off piston of a shut-off valve which activates at least one fluid-carrying connecting line of the valve device, and a fluid-carrying control line which discharges from the connecting line into the fluid chamber of the shut-off piston which can be moved in the direction of a second valve seat by a second energy storage device.

The hydraulic valve device according to the invention can be generically assigned to the so-called pilot-operated check valves which interact largely with directional valves and which are used to control a load. To initiate unblocking of the check valve, either an auxiliary pressure is connected via the directional valve, or the activating pressure of the directional valve is used directly. The auxiliary or activating pressure is then used as a so-called striking pressure in order to open a pilot valve which relieves the back of the shut-off piston. The load pressure in the working port then acts continuously on an annular surface on the shut-off piston and is opposed to the spring force of the now unloaded back. The activation piston of the pilot valve can then be oriented such that after opening of the pilot valve it also presses the shut-off piston in the opening direction. The activation piston of the pilot valve therefore presses from the side of the fluid-carrying, channel-like connecting line to the directional control valve on the indicated shut-off piston and there opens a pilot valve from the spring chamber of the shut-off piston into the connecting channel which is connected to the return of the entire valve device in this operating state.

Therefore, there is a throttled connection between the load side and the back via which a continuous control oil flow drains via the pilot valve to the low pressure or tank port of the device during unblocking. Then the hydraulic consumer connected to the respective operating port under load decreases by this leakage flow without the possibility of exerting any influence on the control piston with the control slide generally in the form of a control piston. Accordingly, two fundamental control concepts are distinguished:

-   1. The control oil is routed into the return channel of the     hydraulic device via the control piston. In the neutral position,     the control piston establishes throttled relief to the shut-off     piston so that it can be placed clearly on its pertinent valve seat     without an oil volume being clamped between the valve seat and the     control piston. For unblocking at very low loads the throttled     relief must, however, be opened as far as possible so that the load     pressure can also lift the shut-off piston. In order to be able to     cover all conceivable load cases, major relief must be chosen which     leads to the minimum speed being high when starting up with high     loads; this is perceived as unsafe in operation. -   2. The control oil is connected past the control piston directly to     the leak port or a return port R. The relief throttle on the control     piston for the shut-off piston can be chosen to be very small     because relief of the back of the shut-off piston is independent of     precision control of the control slide. But, in turn, the large     control oil flow through the pilot valve is disadvantageous under     high loads.

The smallest required lowering flow can be assumed to be about 1 l/min. The leakage flow, depending on the design and level of the load pressure, can, however, assume a multiple thereof and thus is no longer acceptable. In particular, the connected machine can no longer be controlled with sufficient precision in the precision control range at high pressures.

In practice, various solutions are known for actuating the activation piston on the pilot valve. Mutual striking is mechanically simple under the action of the inflow pressure; however, for so-called leading loads the inflow pressure can collapse, and a cycle of closing and opening of the shut-off piston begins, accompanied by jerky movements of the connected hydraulic device. Improvement of operation yields an opening pressure which is independent of load in the form of the activating pressure for the control piston or control slide. This structure, however, leads to complicated channel routing within the valve device, and the activation piston which sits in the middle of the valve has a long control axis; this is accompanied by an increase in the overall size of the valve (WO 2006/105765 A1).

DE 199 19 014 A1 discloses another valve device with a pilot-controlled check valve for activating two working ports. In the known solution, the working pressure of the working port, which is under the inflow pressure, presses on the check valve of the opposite side. In the case of the leading loads, the inflow pressure then drops to the atmospheric pressure and the striking pressure can collapse. As a result, the check valve closes and the hydraulic consumer can shut down. In this case, the inflow pressure in turn rises spontaneously, and the check valve opens and accelerates the load until it leads again. The described control period then starts again from the beginning.

US 2002/0029810 A1 discloses a valve device in which unblocking is initiated via the control piston, for which a pilot valve which lies transversely to the axis of the control piston is used. The pilot valve which is arranged transversely in this way must be connected to the assigned connecting lines in a mechanically difficult manner and increases the valve installation height by a considerable amount. To increase production reliability, the aforementioned pilot valve is supported in an independent sleeve of the valve device. DE 10 2005 033 577 A1 describes in turn pilot valves which are mechanically struck and to reduce the transverse force on the control piston are not axially actuated, but are tilted in the manner of a pivoting motion. Mechanical unlocking is furthermore ready for operation in a possible failure of the hydraulic energy, the technical mechanical effort for triggering the pilot valves, however, being considerable, especially because an additional attachment housing must be provided which bears the pilot valves and a thin connecting bore must be routed from the respective check valve to the opposite side.

DE 103 25 294 A1 discloses a generic valve device in the manner of a hydraulic control arrangement for activation of a consumer independently of the load, with a housing section, preferably made as a valve disk in which a continuously adjustable directional valve which controls the flow of the pressurized fluid to the consumer is accommodated and to which an individual pressure compensator is assigned, and with at least one shut-off valve which is located in the flow path of the pressurized fluid between the directional valve and the consumer and which can be unblocked to enable flow of the pressurized fluid from the assigned consumer port, and with a replenishment valve via which pressurized fluid from the tank can be replenished when the consumer is undersupplied. In that, in the known solution, the shut-off valve is piloted via a pilot valve whose axis runs perpendicular to the axis of the directional valve and of the shut-off valve which is located axially parallel to it, the pilot valve being mechanically openable via a valve slide of the directional valve, and because the axis of the pressure limiting and replenishment valve runs perpendicular to the axes of the directional valve and of the pilot valve, the known solution is characterized by particular compactness, all essential components necessary in a so-called LUDV system being accommodated with minimum installation space.

Proceeding from this prior art, the object of the invention is to devise a valve device of mechanically simple structure which is likewise compact and reliable in operation and which ensures that leading loads cannot adversely affect unblocking. This object is achieved by a hydraulic valve device with the features of claim 1 in its entirety.

The hydraulic valve device according to the invention is characterized in that the pilot piston of the pilot valve and the shut-off piston of the shut-off valve are guided within the valve housing to be able to move parallel to one another and that the pilot piston and the shut-off piston can be moved in opposite directions to their respectively assignable valve seat by the action of at least one of the two energy storage devices. The seat-sealed pilot valve which is used here with its pilot piston relieves the back of the shut-off piston toward the tank and not as in the known solutions toward the control piston axis. The pilot valve here is activated by the unlocking pressure in the fluid activation line, this unlocking pressure Y being independent of the load and preferably being applied by an actuating device. Accordingly, the unblocking is not adversely affected by way of leading loads. Instead of the unlocking pressure Y, the actuating device can also use an actuating magnet for activating the activation piston.

The pilot valve is located in a space-saving manner on the back of the shut-off piston and on its middle axis such that its seat-sealed pilot piston projects into the spring chamber of the shut-off piston. The activating or striking piston of the pilot valve is therefore supported in the valve housing along the return valve axis, and since the opening stroke of the pilot valve is greater than that of the shut-off piston, reliable operation is ensured.

The pilot-operated check valve in the form of the hydraulic valve device is located axially parallel to the control piston so that space-saving installation within the directional valve is possible. Furthermore, secondary leak flows via the control line do not occur; this increases operating reliability.

In one especially preferred embodiment of the valve device according to the invention, the pilot-operated check valve is provided with a double seat-sealed function. The additional seat-sealed check valve is installed in the shut-off piston such that it opens from the inflow channel into the spring chamber. In this way, the inflow pressure in the spring chamber of the main shut-off piston can be represented and prevents the shut-off piston from opening unintentionally. Only when the seat-sealed pilot valve formed by the activation piston with a pilot valve on the back is actively opened can the shut-off piston also open in the flow direction. This also results in improved closing and passively holding closed for the valve device. So that a leak oil flow does not flow from the spring chamber provided with inflow pressure into the load space while being held closed with the shut-off piston, the throttle site to the load space is provided with an additional valve device with a valve part preferably in the form of a closing ball. The valve device opens in flow from the load space into the spring chamber of the shut-off valve. When the double seat-sealed shut-off piston is closed, the necessary displacement volume can furthermore flow into the spring chamber, but, conversely, a leak in the outflow direction (for example, toward a steering cylinder) cannot occur. Thus the indicated valve device is tight in both possible throughflow directions. This configuration is advantageously used for safety applications, which generally require redundant control concepts.

The invention is detailed below using exemplary embodiments shown in the drawings. The figures are schematic and not to scale.

FIG. 1 is a longitudinal section of a first embodiment through the hydraulic valve device according to the invention;

FIG. 2 is a representation of a modified version corresponding to FIG. 1, and

FIG. 3 is a front view of the installation situation of the valve device as shown in FIG. 1 in a conventional directional valve arrangement.

The hydraulic valve device as shown in FIG. 1 has a valve housing 10 which can be secured as a screw-in cartridge over a screw-in distance 12 on housing parts 14 of a third component, for example, in the form of a directional valve (see FIG. 3). In the valve housing 10 an activation piston 16 is guided to be able to move lengthwise and activates a pilot valve 20 in an actuatable manner by an actuating device designated as a whole as 18, by means of which pilot valve a fluid port T in the form of a low pressure or tank port in the valve housing 10 can be connected to a fluid chamber 22 of a shut-off piston 24. A fluid-carrying connecting line 1, 2 of the valve device can be activated by means of the shut-off piston 24. The shut-off piston 24 furthermore has a fluid-carrying control line 26 which discharges into the fluid chamber 22 of the shut-off piston 24 from the connecting line 1, 2. The actuating device 18 has a fluid activation line Y which routes the so-called unlocking pressure of the actuating device 18 to the back of the activation piston 16. How the fluid activation line Y is exposed to the unlocking pressure is detailed below.

As FIG. 1 furthermore shows, by means of a first energy storage device 28 in the form of a compression spring, the pilot valve 20 is movably held in the direction of a valve seat 30 of the valve housing 10, and by means of a second energy storage device 32, likewise in the form of a compression spring, the shut-off piston 24 can be moved in the opposite direction onto a further second valve seat 34 which also borders the fluid-carrying connecting line 1, 2 as a wall part. The two energy storage devices 28, 32 are routed within the fluid chamber 22, and the second energy storage device 32 in the form of a compression spring encompasses the first energy storage device 28 with its assignable compression spring. The first energy storage device 28 is supported with its one free end on the inside of the control piston 24 and with its other end adjoins the end side of the pilot valve 20. The second energy storage device 32 is likewise supported on the same inner side of the control piston 24 and with its other end adjoins the free end side of the valve housing 10 which is connected to the fluid chamber 22 to carry fluid and forms a boundary wall of the fluid chamber. In this respect, the indicated face-side boundary wall forms a stop 36 which the shut-off piston 24 can strike in its rightmost travel position with its released enclosure wall 38.

At the site at which the fluid-carrying control line 26 discharges into the fluid chamber 22 of the shut-off piston 24, there is a discharge site 40 which can be closed by the free face end of the pilot valve 20. For this termination, the discharge site 40 is conically widened toward the fluid chamber 22 of the shut-off piston 24, and the pilot valve 20 on its free face side has a spherical closing cap 42 which can engage the discharge site 40 to form a seal. A throttle site 44 in the form of a throttle bore is located between the discharge site 40 and the other fluid-carrying control line 26. The spherical closing cap 42 of the pilot valve 20 on its bottom has a conically running sealing surface 46 which can be brought into contact with an additional conical sealing surface 48 of the valve housing 10, for obtaining a line-shaped sealing site 50 as the first valve seat 30 the incline of the other sealing surface 48 being chosen to be smaller than for the sealing surface 46 of the pilot valve 20. In the closed state of the valve device as shown in FIG. 1, the first energy storage device 28 presses the pilot valve 20 against the indicated first valve seat 30.

Furthermore, the pilot valve 20 has a bridge-like extension 52 which establishes a connection between the pilot valve 20 and the activation piston 16. This connection can be in one piece. The inherently cylindrical activation piston 16 has through bores 54 which discharge into the cross channel 56 which emerges in turn into an annulus 58 which in each travel position of the activation piston 16 has a fluid-carrying connection to the fluid port T within the valve housing 10. Otherwise, the bridge-like extension 52 is routed in a widened through channel 60 in the valve housing 10 so that with the pilot valve 20 open, the first valve seat 30 is released, with the result that a fluid-carrying connection exists between a part 2 of the connecting line 1, 2 and the fluid port T, via the fluid-carrying control line 26, the throttle site 44, the discharge site 40, the fluid chamber 22, the through channel 60, the through bores 54, the cross channel 56, and the annulus 58.

The fluid activation line Y is moreover permanently connected to the chamber space 64 of the activation piston 16 via a throttle connection site 62 to carry fluid, the chamber space 64 as already described with the pilot valve 28 open establishing a fluid connection between the fluid port T in the valve housing 10 and the fluid chamber 22 of the shut-off piston 24. For a fluid-carrying connection of the chamber space 64 to the throttle connection site 62, in turn the cross channel 56 and the annuli 58 which are made in the lengthwise direction and which are located opposite one another diametrically to the longitudinal axis of the pilot valve 20 are used. Furthermore, the annulus 58 is separated fluid-tight from the chamber space 64 via a periphery-side widening 66 on the outer periphery of the activation piston 16.

To activate hydraulic equipment, in this case in the form of a hydraulic working cylinder 68, part 2 of the connecting line 1, 2 is connected to the so-called piston side 70 of the working cylinder 68 to carry fluid. The rod side 72 is in turn connected to a hydraulic control device which is not detailed and which is, however, omitted for the time being for the following simplified examination of operation. Moreover, depending on the actuating situation of the actuating device 18, for operation of the device, part 1 of the connecting line 1, 2 is connected to a pressure supply source, for example, in the form of a hydraulic pump by way of a pressure supply port P (see FIG. 3), or the actuating device 18 switches part 1 of the connecting line 1, 2 so as to be unpressurized, by part 1 being connected to a return port R.

At this point, for better understanding, the manner of operation of the hydraulic valve device as shown in FIG. 1 will be detailed below. To lift a load, the hydraulic working cylinder 68 on the piston side 70 must be activated so that the cylinder can be extended. For this process, the pressure-carrying part 1 of the connecting line 1, 2 must be connected to part 2 which is connected to the piston side 70 to carry fluid. The rising pressure in part 1 as the inflow exceeds the prevailing load pressure in part 2 of the port of the piston side 70 so that the shut-off piston 24 is moved to the right against the action of the second energy storage device 32, viewed in the direction of FIG. 1. Then a volumetric flow begins to flow from part 1 to part 2, and the shut-off piston 26 opens until equilibrium of forces has been established as a result of the pressure drop on the second valve seat 34. In the indicated opening motion, the shut-off piston 24, according to its stroke volume in the fluid chamber 22, pushes oil from its back via the throttle site 44 into the load pressure space which is partially formed by part 2 of the connecting line 1, 2, and the maximum opening stroke is limited by the shut-off piston 24 striking the stop 36 of the valve housing 10.

To lower the load at which the piston rod unit of the working cylinder 68 is retracted again in the direction of the piston side 70, in the fluid activation line Y a corresponding unlocking pressure is applied which moves the activation piston 16 viewed in the direction of FIG. 1 from right to left, and, in doing so, entrains the pilot valve 20 to the left by way of the pilot piston in the form of the extension 52, the pilot valve 20 clearing the first valve seat 30. With this opening of the fluid path via the through channel 60, the pressure on the back of the shut-off piston 24 and therefore in the fluid chamber 22 is suddenly reduced, and a corresponding control oil flow flows to the fluid port T in the valve housing 10. At the same time, the shut-off piston 24 moves toward the pilot valve 20, and the shut-off piston 24 is set directly on the pilot valve 20; the discharge site 40 and therefore the throttle site 44 are closed fluid-tight. The leak flow which flows briefly to the fluid port T is then shut off. The high opening force of the load pressure which prevails on the piston side 70 of the working cylinder 68 acts on the free annular surface on the shut-off piston 24 and moves the pilot valve 20 back to the right in its direction which blocks the valve seat 30. When the shut-off piston 24 is, however, stationary on its stop, the pilot valve 20 is still open, and the back of the shut-off piston 24 with its fluid chamber 22 remains connected to the fluid port T.

Even with leading loads, unblocking is not adversely affected and can be reliably carried out. With the valve device according to the invention, a secondary leak flow with uncontrolled lowering motion by a second seat valve between the pilot valve and shut-off piston, as shown to some extent in the prior art, is definitely avoided. The lowering motion is induced only by way of the actuating device 18 and is reliably carried out. Otherwise, the matching between the throttle site 44 in the shut-off piston 24 with the relief channels is not critical because the indicated throttle connecting site 44 is immediately closed again after opening by means of the pilot valve 20. Therefore, back pressures cannot form in the relief line and on the back. In this respect, at very low load pressures on the working cylinder 68, the shut-off piston 24 can also be raised without delay off its valve seat 34 in order to ensure unobstructed fluid return from part 2 to part 1 of the connecting line 1, 2, and, in this return case, part 1 of the connecting line 1, 2, as already described, is to be connected to the return port R by an actuating device 18.

The use of a pilot-operated check valve according to the aforementioned description is detailed below using a directional valve solution as shown in FIG. 3 as part of the hydraulic valve device. In this respect, the relationships of the pilot-operated check valve with the actuating device 18 is detailed. FIG. 3 shows a directional valve which is designated as a whole as 74. This directional valve structure is conventional in the prior art so that it will not be further detailed here, but only as necessary for understanding of the check valve solution according to the invention. The directional valve 74 has a multi-part control housing 76 with a plurality of fluid lines and fluid ports. Thus, the fluid port arrangement, among other contributory factors, has a pressure supply port P, a return port R, a section-load sensing port LS, two control ports P′_(A) and P′_(B), as well as two working ports A, B. A pressure compensator 78 which is connected upstream of the individual fluid ports is used to activate the indicated fluid port arrangement.

A control device designated as a whole as 80, in the conventional manner which is not further detailed, has two pilot control valves 82, which are used among other purposes to activate a control piston 84 which is shown in FIG. 3 in its undeflected middle or neutral position. This middle or neutral position can also be supported accordingly by a spring storage means 86. Furthermore, the hydraulic working cylinder 68 is connected in turn to the working ports A, B, the piston side 70 in turn being connected to part 2 of the connecting line 1, 2 to carry fluid via the working port B, and this time the rod space 72 is connected to the working port A by way of a fluid-carrying connecting line so that the directional valve 74 can also activate the rod side accordingly. For the working ports A, B, the pilot-operated check valve is connected upstream according to the solution as shown in FIG. 1.

For the process of lifting a load or the extension process of the aforementioned piston rod unit, the control piston 84 is moved to the right by the actuating device 18, viewed in the direction of FIG. 3, and part 1 of the connecting line 1, 2 is connected to the control port P′_(B) to carry fluid. As a result of the associated inflow pressure, the shut-off piston 24 opens and the supply pressure P′_(B) prevails on the working port B. In this extension motion, the oil volume is displaced out of the rod space 72 via the working port A, and by unblocking the check valve which is responsible for the working port A the draining amount of oil thus travels in the direction of the return port R. If the piston rod unit is to be retracted in the direction of the piston side 70, under the influence of the actuating device 18 which can be activated by an operator the control piston 84 is moved from right to left and part 1 of the connecting line 1, 2 connected to the return port R is switched essentially unpressurized. The control pressure prevailing on P′_(B) is then relayed to the fluid activation line Y via the cross channel 88 and then the unblocking process is carried out. Alternatively, the cross channel 88 can be connected to the lower pressure of the control circuit or directly to the pressure output of the pilot control valves 82. The hydraulically pilot-operated check valve which is responsible for the working port A then undertakes pressure supply for the retraction process by way of the pressurized control port P′_(A). In this respect, the control pressure in the control port P′_(A) if necessary is also used to initiate the described unblocking process on the back of the check valve for the working port A.

The control piston of the directional valve 74 which is designated as 84 is also referred to as a control slide in the technical jargon, and, as an actuating device 18, an actuating magnet which is not detailed can replace the fluid activation line Y, for example, in the form of a proportional magnet which when electrically energized accordingly activates the activation piston 16 with the pilot valve 20 for hydraulic unblocking. The purely fluidic solution presented here, however, has the advantage that actuating current need not be made available for use of the directional valve 74, except for the pilot control valves 82. As already explained in the foregoing, the pilot-operated check valve can be used as a hydraulic valve device only for activation of the working port and a hydraulic consumer. The illustrated hydraulic working cylinder 68 can also be replaced by another hydraulically actuatable working device, for example, in the form of a hydraulic pivoting motor (not shown) and the like.

The altered embodiment as shown in FIG. 2 is explained only to the extent it differs dramatically from the embodiment as shown in FIG. 1. Here, the same components with the same reference numbers are also shown, the aforementioned then also applying to the altered embodiment. The altered embodiment as shown in FIG. 2 is modified such that on the left free end of the shut-off piston 24 an additional valve device 90 is used with a valve part 92 in the form of a closing ball which, routed in the wall parts of the shut-off piston 24, activates a connecting site 94 to part 1 of the connecting line 1, 2 in terms of fluid flow. Furthermore, the fluid-carrying control line 26 is divided within the shut-off piston 24 into two fluid-carrying branches 96, 98, as shown in FIG. 2, the valve part 92 shutting off the branch 96 to part 2 of the connecting line 1, 2.

If the pilot-operated check valve as shown in FIG. 2 is to be opened, that is, if a fluid-carrying connection is to be established between the parts 1 and 2 of the connecting line 1, 2, first of all the inflow pressure in part 1 prevails in the fluid chamber 22 via the valve device 90 and the second branch 98. In this respect, therefore the valve part 92 shuts off only the first branch 96. But since the pressure in the fluid chamber 22 corresponds to the inflow pressure in part 1 of the connecting line 1, 2, the shut-off piston does not open and only when the pilot valve which is seat-sealed in this way is actively opened or unblocked on the back, as described, by way of the fluid activation line Y or an actuating magnet, the shut-off piston 24 by movement to the right as viewed in the direction of FIG. 2 also opens the fluid path from part 1 to part 2 of the connecting line 1, 2 because the pressure in the fluid chamber 22 can be relieved to the port line T.

In addition to this defined opening process, closing and passively keeping closed are also improved. If, when the load is lowered or the piston rod unit is retracted into the working cylinder 68, in the valve position shown in FIG. 2 there is a higher fluid pressure in part 2 of the connecting line 1, 2, this pressure acts via the first branch 96 on the valve part 92 which in this respect is moving to the left within the valve chamber and closes the port site 94. In this way, the two branches 96, 98 are then connected to one another to carry fluid and the fluid pressure in part 2 also prevails in the fluid chamber 22. If, in turn, the corresponding unblocking is carried out via the actuating device 18, in turn the shut-off piston 24 opens in the already described manner and the fluid pressure in part 2 is transferred to part 1 of the fluid line 1, 2, part 1 being connected to the largely unpressurized return port R of the described directional valve 74 to carry fluid via the control piston 84 of the actuating device 18. For the described activation processes, the two fluid-carrying branches 96, 98 each have a throttle site formed by a cross section reduction 100, 102.

Thus the hydraulic valve device according to the invention is tight in both flow directions and a double seat-sealed pilot-operated check valve is formed. The alternative embodiment shown in FIG. 2 with the corresponding installation position can in turn replace the pilot-operated check valves as shown in FIG. 3 and can lead to improved operation of the directional valve 74 in the described scope. 

1. A hydraulic valve device having a valve housing (10), with a pilot piston of a pilot valve (20), which piston can be actuated by an actuating device (18), and which piston can be moved in the direction of the valve seat (30) of the valve housing (10) by means of a first energy storage device (28), by means of the pilot piston a fluid port (T) in the valve housing (10) being connectable to a fluid chamber (22) of a shut-off piston (24) of a shut-off valve which activates at least one fluid-carrying connecting line (1, 2) of the valve device, and a fluid-carrying control line (26) which discharges from the connecting line (1, 2) into the fluid chamber (22) of the shut-off piston (24) which can be moved in the direction of a second valve seat (34) by a second energy storage device (32), characterized in that the pilot piston of the pilot valve (20) and the shut-off piston (24) of the shut-off valve are guided within the valve housing (10) to be able to move parallel to one another and that the pilot piston and the shut-off piston (24) can be moved in the opposite direction to their respectively assignable valve seat (30; 34) by the action of at least one of the two energy storage devices (28, 32).
 2. The valve device according to claim 1, characterized in that the actuating device (18) has an actuating magnet or a fluid activation line (Y) which induces movement of the activation piston (16) with the capacity to be pressurized with fluid pressure by the control piston (84) of the valve device.
 3. The valve device according to claim 1, characterized in that a discharge site (40) at which the fluid-carrying control line (26) discharges into the fluid chamber (22) of the shut-off piston (24) can be closed by the pilot valve (20).
 4. The valve device according to claim 1, characterized in that the fluid-carrying control line (26) is divided into two fluid-carrying branches (96, 98), each of which with its one end discharges into a valve chamber (99) of a valve device (90) and with their other end into one part (2) of the connecting line (1, 2) or into the fluid chamber (22).
 5. The valve device according to claim 4, characterized in that the valve device (90) has a valve part (92), preferably in the form of a valve ball which, routed in wall parts of the shut-off piston (24), activates a connecting site (94) of the valve device (90) in terms of fluid flow.
 6. The valve device according to claim 1, characterized in that the fluid port (T) in the valve housing (10) is a low pressure port, especially a tank port.
 7. The valve device according to claim 2, characterized in that the fluid activation line (Y) is permanently connected to the chamber space (64) of the activation piston (16) via a throttle connection site (62) to carry fluid and that the chamber space (64) with the pilot valve (28) open establishes a fluid connection between the fluid port (T) in the valve housing (10) and the fluid chamber (22) of the shut-off piston (24).
 8. The valve device according to claim 2, characterized in that the control piston (84) for activating a device (68) which is connected to at least one working port (A, B) of the valve device clears or shuts off the fluid-carrying connecting line (1, 2) by means of the shut-off piston (24).
 9. The valve device according to claim 8, characterized in that there is one shut-off piston (24) which can be activated by means of the pilot valve (20) for each working port (A, B) that can be activated by means of the control piston (84). 